Millstone.



T. L. & T. J. STURTEVANT.

MILLSTONE.

APPLICATION FILED NOV. 25, 1910.

1 ,1 1 1 ,043. Patented Sept. 22, 1914 THE NORRIS PETERS CO.,-PHOTOLITHO.4 WASHINGTON, D.

e of the United tached to one of the bands of the composite millstones rrroa.

A CORPORATION OF MAINE.

MILLS'I'ONE.

Specification of Letters Patent. Application filed November 25. 1510.

Patented Sept. 22, late. Serial No. 594,196.

To all whom it may concern- Be it known that we, THOMAS L. STURTE- VANT and THOMAS J. STURTEVANT, citizens States, residing, respectively, at Quincy and Wellesley, in the county of Norfolk and State of Massachusetts, have invented or discovered certain new and useful Improvements in Millstones, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to that class of composite millstones comprising blocks of rock emery or other suitable hard abrasive material held in place by a metallic filling in which the abrasive blocks are embedded and which metallic filling is applied in a molten condition, so that the blocks will be strongly embedded therein. Composite millstones, of the class referred to, are well. adapted for rapid grinding, in that they are not damaged by heat generated by running the stones at a high speed, as are French bur millstones, which are solid and are liable to crack if much heated. These fast-running composite millstones, however, are very heavy and must be secured together and to their carriers with much greater strength than ordinary or solid-block millstones, owing to the great strain to which such heavy stones are subjected in rapid grinding.

In carrying the present invention into effect the composite millstones comprise wedge-shaped or tapering metal blocks at their back peripheral portions and which blocks are bolted or otherwise strongly ator hoops with which these millstones are provided, and are also set deeply into the metal filling of the stone; and theinvention in its preferred form will also comprise wedge-shaped or tapering blocks or blocks of a strongly holding shape located between the peripheries and their cen tral portions and providing means for strongly securing the millstones to their carriers, and also for securing the back hoop or band to the millstone. These wedgeshaped or tapering blocks of any holding shape are so disposed that their wider or holding portions are toward the grinding faces of the millstones, and as they are embedded in the metallic filling which also holds the grinding blocks in place they'afford greatly increased strength for securing the bands to the millstones and the millstones totheir carriers, so that the strength of the millstones, as also the strength of their attachments to their carriers is greatly increased by the improved construction.

Tn the operation of the millstones of the class to which the present invention relates, those portions of the millstones nearest their peripheries run the fastest, so that each inch of grinding surface near the periphery of a stone is more efi'ective, in the grinding operation, than several inches of surface near the eye of the stone where the movement is much slower. The emery blocks forming the grinding portions of these composite stones are very hard and intractible, and are of very irregular shape. Heretofore blocks have been selected so as to fill the faces of stones, near their peripheries, as nearly as possible, but owing to the irregular forms of these blocks the faces of composite millstones, as heretofore constructed, have frequently been weak and greatly lacking in continuity at their peripheral portions where the greatest grinding efi'ect is secured. In the present improved millstone the emery blocks are shaped or formed convex on their outer faces so as to conform more or less closely in curvature to the curvature of the bands of the stones. This shaping of the blocks is more or less expensive, owing to their hard and intractible character, but the reatly increased efiiciency resulting from forming these composite millstones with practically continuous grinding or emery-stone faces near their peripheral portions warrants the greater expense of con struction.

In the accompanying drawings Figures .1 and 2 are face and back views, respectively, of a millstone embodying the present invention. Fig. 3 is a partial sectional view of the same. Figs. 4c and 5 are detail views of different forms of tapering or wedge-shaped blocks which may be employed.

Referring to the drawings, 12 denotes the improved composite millstone which comprises abrasive blooks 13, preferablyof rock emery, embedded in a metallic filling 14 preferably poured in or around the blocks 1 13 in a molten condition. Also embedded in the metallic filling 14 are tapering metal blocks '15 which are preferably provided v with flanges 16 the central portion stone is running.

by which they may be bolted or riveted to the back band or hoop 17 of the stone, so as to be permanently attached to said hand, these blocks being also preferably provided with threaded holes 18 for the insertion of screw-bolts to attach the composite millstone to its carrier. Also embedded in the metallic filling are wedge-shaped metal blocks 19, in the preferred form of the invention, these blocks 19 being arranged between the periphery of the millstone and thereof and provided with threaded openings 20 for the reception of screw-bolts to attach them to the millstone carrier. The thicker ortions of these tapering or wedge-shaped lilocks 15 and 19 are at their inner parts, or away from the rear face of the composite stone, so that the said blocks taper outwardly and flare inwardly, to insure a strong holding effect in securing the stone to its carrier. The blocks 15 and 19 are preferably of cast iron. The outer faces of the emery blocks 13, which are disposed near the periphery of the millstone, are preferably formed convex or curved so as to conform to the curvature of the band 17 or approximately so, thereby providing, as nearly as possible, continuous grinding faces near the peripheral or skirt portion of the millstone, or at that portion of the millstone which has the highest speed, and consequently the most eificlency, when the mill- From the foregoing it will be understood that the improved construction provides means for strongly securing the back band or hoop t0 the composite millstone, as also means for strongly attaching the millstone to its carrier, thereby avoiding all danger of the millstone becoming loose when in rapid rotation; while the practically continuous grinding peripheral face portion of the improved millstone willadd considerably to its efficiency.

Having thus described our invention we claim and deslre to secure by Letters Patent 1. A composite millstone comprising 7 blocks of hard abrasive material and a metallic filling in which said blocks are embedded, combined with one or more metalbands or hoops encircling the millstone, and a plurality of inwardly tapering metal blocks also embedded in the metal filling at the back of the peripheral portion of the millstone and permanently attached to one of said bands or hoops, for strongly securing the said band or hoop to the periphery of; the millstone, the said blocks being also adapted for attachment to the millstone carrier.

2. A composite millstone comprising blocks of hard abrasive material and a metallic filling in which said blocks are embedded,

combined with one or more metal bands or hoops'encircling the millstone, a plurality of emery stone,

, portions flaring or outwardly encircling the millstone,

of inwardly flaring or outwardly tapering metal blocks also embedded in the metal fillin g at the back of the peripheral portion of the millstone andpermanently attached to one of said bands or hoops, forstrongly securing the said band cry of the millstone,

or hoop to theperiphthe 'said blocks being also adapted for attachment to the millstone carrier, and an interior set of inwardly flaring or outwardly tapering metal blocks also embedded in the said metallic filling at the back of tihemillstone and adapted for attachment to the millstone carrier.

3. A-composite millstonecomprisingblocks of emery stone, a metallic fillingin which said blocks are embedded, and binding hoops or bands, said emery blocks-being artificially shaped at their peripheral outer face portions to conform to the curvature of the said binding hoops 'or' bands, or approximately so, the said mlllstone also comprising inwardly flaring or outwardly tapering metallic holding blocks embeddedin the metallic filling at its peripheral back portions of said and permanently attached to one hoops or hands.

4. Acompos'ite millstone comprising blocks a metallic filling in which said blocks are embedded, and binding hoops or bands, said emery blocks being artificially shaped at their peripheral outer face to conform to the curvature of'the said binding hoops or bands, or'approximately so, the said millstone also comprising inwardly flaring or outwardly tapering metal holding blocks embedded in themetallic filling at its peripheral back portion and permanently attached to one of said hoops or bands, and other metal inwardly flaring or outwardly tapering holding blocks embedded in said metallic filling between the periphery of the stone and its central part, said metal blocks being adapted for attachment to the millstone carrier.

5'. A composite millstone comprising blocks of hard abrasive material and a metallic filling inwhich said blocks are embedded, combined with one or more metal bands or hoops encircling the millstone, and a plurality of inwardly flaring or outwardly tapering metal blocks also embedded in the metal filling at the back ofthe peripheral portion of the millstone andprovided with flanges by which they are permanently attached to one of said bands or hoops, for strongly securing the said band or' hoop to the peiphery' of the millstone, the said blocks being also adapted for attachment to the millstone carrier.

6. A composite millstone comprising blocks of hard abrasive material and a metallic filling in which said blocks are embedded, combined with one or more metal bands or hoops a plurality of inwardly' flaring or outwardly tapering metal blocks also embedded in the metal filling at the back of the millstone and Which they peripheral portion of the provided with flanges by are permanently attached to one of said bands or hoops, for strongly securing the said band or hoop to the periphery of the millstone, and an interior set of tapering metal blocks also embedded in the said metallic filling at the back of the millstone and adapted for attachment to the millstone carrier.

7. A composite millstone comprising blocks of emery stone, a metallic filling in Which said blocks are embedded, and binding hoops or bands, said emery blocks being artificially shaped at their peripheral outer face portions to conform to the curvature of the said binding hoops or bands, or approximately so.

8. A composite millstone comprising blocks of hard abrasive material and a metallic filling in which said blocks are embedded, combined With a metal band or hoop encircling said millstone, and holding blocks also embedded in said metallic filling at the back Copies of the peripheral portion of the millstone and permanently secured to said band or hoop, said holding blocks being adapted for attachment to the millstone carrier.

9. A composite millstone comprising blocks of hard abrasive material and a metallic filling in Which said blocks are embedded, combined With a metal band or hoop encircling said millstone, holding blocks also embedded in said metallic filling at the back of the peripheral portion of the millstone and permanently secured to said band or hoop, said holding blocks being adapted for attachment to the millstone carrier, and interior holding blocks also embedded in said metallic filling at the back of the millstone, and also adapted for attachment to the millstone carrier.

In testimony whereof We afiiX our signatures, in presence of two Witnesses.

' THOMAS LEGGETT STURTEVANT.

THOMAS JOSEPH STURTEVANT. Witnesses:

W. F. ELLIs, GRACE G. GODFREY.

of this patent may be obtained for in cents each, by addressing the Commissioner of Patents.

Washington, D. G. 

